You can remove them, I have often done that without harming the plants. They produce much more aerial roots when grown in low light, btw.

I once had the true Hatiora gaertneri (Easter cactus). It was about as difficult to grow and flower as the hybrids.

#2 Hoya kerrii

Between 0 and 1 %.

4. A very pale Lobivia arachnacantha?

More likel

Cactusgirl wrote:the cactus looks like Opuntia Ficus-Indica

Not Opuntia (wrong shape, no leaves), probably an epiphyte like Hylocereus.

I can test it too.

In cultivation or in the wild?

I have grown both baccifera ssp. horrida and pilocarpa, and I think this one looks more like horrida. Both flower relatively easily, so it will probably soon be obvious what it is.

Yes, I definitely have this problem. I now cut off the spent flower with a scalpel and dust the wound with sulfur if the weather is cold and damp.